1. Field
Apparatuses consistent with exemplary embodiments relate to a backlight unit (BLU) and a holographic display apparatus including the same, and more particularly, to a BLU for a binocular holographic display apparatus for providing hologram images having different viewpoints to two viewing zones and a binocular holographic display apparatus including the same.
2. Description of the Related Art
Apparatuses requiring the use of glasses, as well as non-glasses apparatuses have been developed for displaying three-dimensional (3D) images. Method of display requiring glasses include polarization glasses methods and shutter glasses methods, and non-glasses methods include lenticular methods and parallax barrier methods. These methods utilize the a binocular parallax of a viewer's two eyes, but are limited in the number of viewpoints that can be displayed. Also, there is discordance between depths recognized by the brain and by a viewer's eyes, often creating eye fatigue.
Practical use of holographic display methods as 3D image display methods capable of providing both concordance between the depths recognized by the brain and by eyes, and a full parallax, has gradually increased. Holographic display methods irradiate and diffracting a reference beam onto a hologram pattern on which an interference pattern is recorded, having been acquired by interfering an object beam reflected from an object with the reference beam, and light reflected from the holographic pattern reproduces an image of the original object. A current holographic display method provides a computer-generated hologram (CGH) as an electric signal to a spatial light modulator rather than directly exposing an original object to light to acquire a hologram pattern. The spatial light modulator may form the hologram pattern according to an input CGH signal to diffract a reference beam in order to generate a 3D image.
However, a spatial light modulator having both a very high resolution and a very large amount of processed data are required to realize a full holographic display method. In order to reduce the amount of processed data, a binocular holographic method is used to provide hologram images only to viewing zones corresponding to an observer's eyes. For example, the binocular holographic method generates only a hologram image having a viewpoint corresponding to a viewing zone of a left eye of the observer and a hologram image having a viewpoint corresponding to a viewing zone of a right eye of the observer and respectively provides the hologram images to the left and right eyes of the observer. In this case, hologram images of any other viewpoints will not be generated, and thus the amount of processed data will be greatly reduced. Also, display apparatuses that are currently commercialized may satisfy the resolution condition of the spatial light modulator.